From c9b92657b415bc1b855c394284efa0e33119ef61 Mon Sep 17 00:00:00 2001
From: Matthias Reichl <hias@horus.com>
Date: Sun, 11 Oct 2015 12:28:30 +0200
Subject: [PATCH] bcm2835-dma: Limit cyclic transfers on lite channels to 32k

Transfers larger than 32k cause repeated clicking with I2S soundcards.
The exact reason is yet unknown, so limit to 32k as bcm2708-dmaengine
did as an intermediate fix.
---
 drivers/dma/bcm2835-dma.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -144,6 +144,12 @@ struct bcm2835_desc {
  */
 #define MAX_LITE_TRANSFER	(SZ_64K - 4)
 
+/*
+ * Transfers larger than 32k cause issues with the bcm2708-i2s driver,
+ * so limit transfer size to 32k as bcm2708-dmaengine did.
+ */
+#define MAX_CYCLIC_LITE_TRANSFER	SZ_32K
+
 static inline struct bcm2835_dmadev *to_bcm2835_dma_dev(struct dma_device *d)
 {
 	return container_of(d, struct bcm2835_dmadev, ddev);
@@ -412,7 +418,7 @@ static struct dma_async_tx_descriptor *b
 	d->c = c;
 	d->dir = direction;
 	if (c->ch >= 8) /* LITE channel */
-		max_size = MAX_LITE_TRANSFER;
+		max_size = MAX_CYCLIC_LITE_TRANSFER;
 	else
 		max_size = MAX_NORMAL_TRANSFER;
 	period_len = min(period_len, max_size);
